With the thin-film transistor technology, transistor switches in a microelectronic circuit can be fulfilled in a display panel whereby the thin-film transistor technology has popularly been applied to display products. As shown in FIG. 1A, while the conductivity of the contact area of the source electrode SP and the conductivity of the contact area of the drain electrode DP in the thin-film transistor increase, the electrode areas of the source electrode and the drain electrode in the thin-film transistor have a lower resistivity and a higher electron mobility.
As shown in FIG. 1A, the conventional method of forming conductor (N+) areas in a thin-film transistor is to dope charged ions into the contact area of the source electrode SP and the contact area of the drain electrode DP in the thin-film transistor in order to increase the conductivity of the contact area of the source electrode SP and the conductivity the contact area of the drain electrode DP. However, the charged ions used in this conventional method easily diffuse to a semiconductor channel CP in the thin-film transistor so that the electrical characteristics of the thin-film transistor are unstable.
Also, referring to FIG. 1B and FIG. 1C, after the thin-film transistor in FIG. 1A is subjected to a follow-up process (e.g. heating), the doped charged ions (e.g. hydrogen ions) may diffuse to the semiconductor channel CP, resulting in the source electrode SP and the drain electrode DP in the thin-film transistor being substantially conducted. Therefore, no matter if the gate electrode GP is applied with a voltage, the equivalent resistance of the thin-film transistor is substantially unchanged. Also, the relationship of the current flowing through the thin-film transistor and the voltage on the gate electrode is shown by the curve C01 in FIG. 1C, where the current flowing through the thin-film transistor is substantially unchanged with the variation of the voltage on the gate electrode.
Without the property of a voltage control current source, such thin-film transistors cannot be used as digital transistor switches or analog transistor amplifiers.